1. Field of the Present Disclosure
The present disclosure relates to an image forming apparatus and a toner amount calculating method.
2. Description of the Related Art
An electrophotographic image forming apparatus such as a printer or a multi function peripheral obtains toner from a toner cartridge and forms an image using the toner. Some of such image forming apparatuses measure a toner consumption amount.
In an electrophotographic image forming apparatus, an electrostatic latent image is formed on a photoconductor drum or the like. An edge electric field appears at a boundary part between a part with a dot of an electrostatic latent image and a part without a dot of an electrostatic latent image, and consequently toner is consumed more than needed. This phenomenon is called “edge effect”. Therefore, a lot of methods have been proposed for calculating a toner consumption amount with taking the edge effect into account.
An image forming apparatus determines an electric field intensity of a target pixel on the basis of an exposure signal of laser light with taking a distribution pattern of a surrounding electrostatic latent image into account, and determines a toner consumption amount on the basis of the electric field intensity.
Further, in an image forming apparatus, an exposure energy of each subpixel is calculated with taking a laser light profile (i.e. a spatial intensity distribution) into account, and a toner consumption amount is calculated on the basis of the exposure energy.
In the aforementioned image forming apparatus, an electric field variation of the target pixel due to the distribution pattern of the electrostatic latent image is estimated using a spatial filter under an assumption that an electric field intensity distribution pattern of each pixel is in inverse proportion to a second power of a distance from the pixel.
However, when the spatial filter has a certain characteristic, in an edge part of a thin line in a printing image, an electric field variation may be estimated to be larger than an increase of an electric field intensity due to influence of actual edge effect, and consequently the toner consumption amount may be calculated to be larger than an actual toner consumption amount.